Hey man. I hope your quest for ear training is going well.
Like most people have said here, learning simple melodies is the way to go. I started trying to learn everything by ear around 4-5 years ago, and what I did was whenever I had a few hours to play within a day, I would dedicate one EXCLUSIVELY to learning simple melodies. Go through whatever music you listen to, whether that'd be rock, jazz, metal, indian music, and try to learn short melodies of things that sound reachable for your level. Don't try to go too complicated. You should be able to play more than a few melodies during that one hour, and within a year or so of doing that, you will become really comfortable with learning just about anything by ear. There's nothing wrong with looking at tabs or a video once in a while, but after a few months, you won't have to.